Impact of Extended-Spectrum β-Lactamase–Producing Escherichia coli and Klebsiella Species on Clinical Outcomes and Hospital Costs: A Matched Cohort Study

Objectives.To evaluate the economic and clinical impact of infection with extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella species (ESBL-EK).Design.A matched-cohort analysis of the cost of illness.Setting.An 810-bed, urban, community hospital in Hartford, Connecticut.Patients.Twenty-one case patients infected with ESBL-EK at a site other than the urinary tract were matched with 21 control subjects infected with a non–ESBL-producing organism on the basis of pathogen species, age, anatomic site of infection, hospitalization in the intensive care unit (ICU) during the time of infection, date of hospitalization, and initial antibiotics received.Results.Mean infection-related costs per patient were significantly greater for case patients than for control patients ($41,353 vs $24,902; P = .034). Infection-related length of stay was the main driver of cost, which was prolonged for case patients, compared with control patients (21 vs 11 days; mean difference, 9.7 days [95% confidence interval {CI}, 3.2-14.6 days] P = .006). The additional cost attributed to the presence of an ESBL-EK infection was $16,450 per patient (95% CI, $965-$31,937). Case patients were more likely than control patients to have clinical failure (P = .027), and the rate of treatment success for case patients whose initial treatment involved antibiotics other than carbapenems was lower than that for their matched control patients (39% vs 83%; P = .013). Treatment was successful in patients for whom initial treatment was with a carbapenem, regardless of the ESBL status of the pathogen.Conclusion.The cost of non–urinary tract infections caused by ESBL-EK was 1.7 times the cost of non–urinary tract infections caused by non-ESBL producers. Prompt recognition and appropriate antimicrobial selection may minimize this ESBL-related impact on hospital costs.